Not sure if sarcasm or not lol - but as it can look complex at a glance, it's just a 5/8" keyed shaft, two cogs & a "BMX" freewheel w/shaft adapter... it looks busy because this particular setup uses additional stop-collars rather then just set screws on the cogs (for spacing & to be sure the bearings stayed put) but more then anything else it's got a disemboweled & reversed rear derailleur arm for a pedal chain tensioner - given it's a multispeed recumbent, that pedal chain is something ridiculous like eight feet long or so (total).
Another difference is this isn't a pedal crank freewheeled setup - so some of the "complexity" is actually simpler, it's jus' all on the jackshaft rather then spread out all over the bike. This jackshaft/freewheel design is FAR less expensive then the specialized shift "kit" freewheel cranksets but more importantly, it's also significantly more reliable as the engine & pedal drives are isolated until the final. Also, unlike with the crank freewheel setups should that freewheel fail, you can still get home
